Butterfly valve for regulating a fluid flow

Abstract

The invention concerns a butterfly valve for regulating a fluid flow rate in particular the air flow rate of an air distributor in an internal combustion engine fuel injector, and the method for making the valve. The valve (1) comprises a housing (2) traversed by a conduit (3) circulating the fluid wherein is provided a butterfly induction shutter (4) mounted on a control axis (5) perpendicular to the conduit axis. The invention is characterized in that it comprises a ring (6) co-axial with the conduit and set between the housing (2) and the induction shutter (4), the ring (6) being made of a material with good dimensional stability and the housing being molded around the ring in a material resistant to the imposed technical constraints and the ring (6) is so arranged that, when the shutter is in closed position, there still is a predetermined clearance between the ring (6) active inner surface (13) and the induction shutter (4) arranged to allow a minimal and time-constant fluid flow rate whatever the variations in humidity or temperature. The invention is applicable to internal combustion engine and any device requiring fluid flow rate regulation.

What is claimed is: 
     
       1. A butterfly valve (1, 21) for controlling the flow of a fluid, in particular the air flow rate entering an air distributor provided in a fuel injection device for an internal combustion engine, said valve comprising a housing (2, 22) made of a molded synthetic material, a conduit (3, 23) arranged in said housing for through fluid flow, a control shaft (5, 25) guided in the housing, a butterfly shutter (4, 24) located at right angles to the conduit and mounted on said control shaft, the butterfly shutter (4, 24) designed to move between a position in which the conduit is closed and the butterfly shutter is oriented substantially perpendicular to the conduit and a position in which the conduit is fully open and the butterfly shutter is oriented substantially parallel to said conduit, wherein the butterfly valve is comprised of a ring (6, 26) with an upstream end and a downstream end coaxial to the conduit (3, 23), the ring inserted between the housing (2, 22) and the butterfly shutter (4, 24), the ring provided with a transverse guide bore (17) designed to receive the shutter's control shaft (5, 25), and comprising an active inner surface (13, 33) forming a seat for said butterfly shutter (4, 24) in the shutter closed position, the ring (6, 26) made of a dimensionally stable preselected material, and the housing (2, 22) of a preselected material molded around said ring, said ring (6, 26) arranged to provide, when the shutter (4, 24) is closed, a set clearance between the ring (6, 26) active inner surface (13, 33) and the butterfly shutter (4, 24), said clearance permitting a minimum fluid flow rate which is time-constant regardless of variations in humidity or temperature. 
     
     
       2. The valve according to claim 1, wherein the housing (2, 22) functions with air distributors of several types of engines and the ring (6, 26) and the shutter (4, 24) are adapted for each type of engine. 
     
     
       3. The valve according to claim 2, wherein the ring (6, 26) and the shutter (4, 24) are made of a material which is selected from the group consisting of metals, metal alloys, thermosetting and thermoplastic synthetic materials. 
     
     
       4. The valve according to claim 2, wherein the housing (2, 22) is made of a material chosen from the thermoplastic synthetic materials. 
     
     
       5. The valve according to claim 2, wherein the ring's active inner surface (13) presents a substantially cylindrical basic form. 
     
     
       6. The valve according to claim 1, wherein the ring's active inner surface (33) presents a complex form provided with at least one partially spherical zone (27) provided at the ring downstream end in the shutter's (24) opening direction, said zone being designed to allow a progressive flow of fluid to pass through at least when the shutter starts to open. 
     
     
       7. The valve according to claim 1, wherein the ring (6, 26) extends inside the housing (2, 22) perpendicular to the conduit (3, 23) shaft, the guide bore (17) being provided in an extension (16), a contact surface between the housing (2, 22) and the ring (6, 26) forming a tightness zone, and a contact surface between the ring (6, 26) and the shaft (5, 25) also forming a tightness zone. 
     
     
       8. The valve according to claim 1, wherein the ring (6, 26) comprises at both upstream and downstream ends, away from its active inner surface (13, 33), at least one thinner internal peripheral zone (A) designed to be deformed when the housing (2) is duplicate molded. 
     
     
       9. The valve according to claim 8, wherein the ring (6, 26) comprises at both upstream and downstream ends a ring-shaped groove (18) delimiting an outer ring-shaped lip (20) and an inner ring-shaped lip (19), the inner ring-shaped lip forming said thinner zone (A). 
     
     
       10. The valve according to claim 1, wherein the housing (2) is added onto an air distributor (40). 
     
     
       11. The valve according to claim 1, wherein the housing (2) is incorporated into an air distributor (50). 
     
     
       12. The method of manufacturing a butterfly valve which comprises the steps of: forming a ring of pre-selected material and internal geometry sized to suit a specific butterfly valve application;   inserting said ring into a mold;   molding a butterfly valve housing from synthetic material incorporating said ring and forming a conduit shaped for fluid passage through said housing;   selecting a pre-manufactured butterfly shutter sized to permit fluid flow around said shutter and within said ring geometry;   inserting said shutter into said molded housing; and   mounting rotatably said shutter into said molded housing with conduit;   wherein said shutter is oriented substantially perpendicular to said conduit in a valve closed position and said shutter is oriented substantially parallel to said conduit in a valve open position.   
     
     
       13. The method of manufacturing a butterfly valve of claim 12 further comprising the steps of: inserting at least one spindle with one end of selected outer form and a second end dimensionally matching said ring inner surface, with said second end adjacent to said ring;   molding said housing incorporating said at least one spindle form within said conduit.   
     
     
       14. The method of manufacturing a butterfly valve of claim 12 further comprising the steps of: manufacturing a plurality of said spindle shapes;   molding said housing applying said plurality of spindle shapes;   wherein said ring geometry and said conduit shape are varied to suit specific butterfly valve applications.   
     
     
       15. The method of manufacturing a butterfly valve of claim 14 further comprises the steps of: providing a bore in said ring of a selected internal diameter;   providing a control shaft with said control shaft diameter corresponding to said bore internal diameter;   mounting fixedly said shutter on said control shaft;   mounting rotatably said control shaft within said ring bore.   
     
     
       16. The method of manufacturing a butterfly valve according to claim 12 further comprising the steps in the order of: placing the shaft in a first mold, with the ring;   molding the ring around the shaft creating a shaft-ring set;   placing said shaft-ring set in a second mold;   molding said shaft-ring set within said housing and said shutter.   
     
     
       17. The method of manufacturing a butterfly valve according to claim 16 further comprising the steps of: providing roughness on said shaft;   forming a catching zone at said roughness;   mounting said shutter on said catching zone.   
     
     
       18. The method of manufacturing a butterfly valve according to claim 12 further comprising steps of: adapting the geometry of said ring according to a form specific to automobile air distributor fuel injection devices for internal combustion engines.   
     
     
       19. The method of manufacturing a butterfly valve according to claim 18 further comprising the steps of: molding said butterfly housing and a automobile air distributor in one piece, in one operation.   
     
     
       20. The method of manufacturing a butterfly valve according to claim 12 further comprising the steps of: molding said housing of a material chemically compatible with said ring;   wherein said housing and said ring adhere to each other ensuring a tight bond between the housing and the ring.